Bronchitis is inflammation of the main air passages to the lungs. Bronchitis may be short-lived (acute) or chronic, meaning that it lasts a long time and often recurs.
Acute bronchitis generally follows a viral respiratory infection. At first, it affects your nose, sinuses, and throat and then spreads to the lungs. Sometimes, you may get another (secondary) bacterial infection in the airways. This means that bacteria infect the airways, in addition to the virus. Chronic bronchitis is a long-term condition. People have a cough that produces excessive mucus. To be diagnosed with chronic bronchitis, you must have a cough with mucus most days of the month for at least 3 months. Chronic bronchitis is one type of chronic obstructive pulmonary disease, or COPD for short. (Emphysema is another type of COPD)